Improved artificial millstone



C. RANDS.

Artificial Millstone.

Patented Nov. 8, 1864.

UNITED STATES CHRISTOPHER RANDS, OF ENGLEWOOD, NEW JERSEY.

IMPROVED ARTIFlClAl. WllLLSTONEa Specilieation forming part of LettersPatent No. 4%@73, dated November 8, 1864.

To all whom it may concerne Be it known that- I, OHRISTOPHER RANDs,

ot' Englewood, County of Bergen, and State of New Jersey, have inventeda new and lmproved Artificial Millstone; and I do hereby declare thatthe following is a full, olear, and exaot description thereof, whichwill enable others skilled in the art to make and use the same,reference being had to the aoeompanying' drawing, which represents afaee View of my invention.

This invention consists in a millstone made of hard or insoluble glass,miXed with corundum or other similar material, and east or pressed in asuitable mold, or formed in any other desirable manner so that by theaetion of the corundum the grinding-surface of the stone is preventedfrom working' sinooth, and a millstone is obtained which will work forany length of time Without being reout or dressed.

The manufacture ot' my millstones is very simple. I take a sufficientquantity of glass, melt it, and mix it with corundum or similar materialor materials and press the stone either solid or in segments, aecordingto the size of the same. I take green glass by preference, because it isthe hardest, and the corundum may be mixed with glass bet'ore it ischased or boled to drive out the air-bubbles.

A stone of this kind presents an even and uniform sul-face. There are nohard and soft spots, no holes in the surface, and the l'urrows a can bereadily produced in the mold, and When once made they will last forever.lt' two stones ot' this kind are rubbed together they do not worksmooth. The land b of each surfaee, by reason of the corundum, willretain sufficient roughness for the purpose of grinding, and grain orother eereals can be ground With a pair of my stones to the finest flouror meal with less trouble and eXpense than With stones of the ordinaryeonstruction.

I am aware that soluble silicates mixed with emery or ground glass havebeen used for grinding-surfaoes, such invention being' desoribed in theEnglish patent of Frederick Ransom, dated December 22, 1858, No. 2,929.He states in his patent that he mixes ground glass or emery With thesoluble silieate and inohls or shapes it into the form of rubbing orgrinding surfaees desired, and, when dried, the molded article issubjeoted to a bright-red heat. In this case the silicate is simply usedas a eement'to hold the emery or gronnd glass, the grinding being'effected entirely by the emery or ground glass. In my artificialmillstone the g'lass itselt' forms the g'rnding-surface, and theeorundum is put in simply to prevent the glass from working smooth.

It is obvious that by mixing soluble glass With emery no millstonescould be produced which would work for half an hour, and the compositionof Mr. Ransom has never, to my knowledge, been used, and, indeed, is notintended for any other purpose bntemery-wheels or deviees for grinding,polishing, or sharpening articles ot' metal. My coinposition would notbe applieable for that pnrpose, and I have intended it merely forartificial millstones.

I claim as new and desire to seoure by Letters Patent An artificialmillstone, produced as herein described, as a new article ofmanufacture.

OHZRI'STOPHER RANDS.

Witnesses:

y JAS. B. HAL'L, U. L. TOPLlFF.

